Southern Africa: South Africa, Swaziland, and Lesotho

The Drakensberg Montane Grassland, Woodland, and Forest ecoregion is the center of southern Africa’s Afromontane region, and is famous for playing a vital role in the restoration of the southern white rhino and black wildebeest. This ecoregion spans the medium altitude areas of the Drakensberg Mountains in South Africa and Swaziland, and the lower slopes of the high altitude Lesotho Plateau. Its vegetation is mainly grassland, but it also contains some of the few stands of conifer forest in Africa. There are also a few patches of grassland occurring in the Stormsberg Mountains, Mount Andersson, and further north in the isolated Soutpansberg and Blouberg Mountains. In all these locations there are high rates of endemism in the flora, and in the fauna, particularly among the reptiles. However, much of the ecoregion has been degraded by farming, afforestation, logging, overgrazing, and burning activities.

Scientific Code

(AT1004)

Ecoregion Category

Afrotropical

Size

78,100 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionThe elevation range of this ecoregion is between 1,800 m and 2,500 m, with the alti-montane ecoregion occurring on the higher slopes of the Drakensberg. Sandstone and shale from the Karoo sequence, together with dolerite intrusions, characterize the geology (Deall et al. 1989; WWF and IUCN 1994; Low and Rebelo 1998). Rainfall ranges from 450 mm per year in the southwest to over 1,100 mm annually in the northeast, with the highest altitudes often receiving 1,900 mm per year. Because of the high precipitation, soils (mostly lithosols) are typically leached, and are rocky and shallow in most places. Cold and wet conditions pervade most of the area, excluding the Lesotho Plateau, where drought can occur in the rain shadow (Low and Rebelo 1998). Temperatures vary between 40o and –13oC, averaging 15oC (White 1983; Low and Rebelo 1998). Although there is little snow, severe frost does occur. These climatic variations result in a highly diversified vegetative community, with montane grassland prevalent on the wet exposed slopes, and forest patches lining the valleys (for details see White 1983; Lubke et al. 1986; Matthews et al. 1993; WWF and IUCN 1994; Burgoyne 1995). As the elevation decreases towards the southeast, montane habitat transitions into thicket and forest, as well as grassland and bushveld savannas (White 1983; Low and Rebelo 1998).

Along the Drakensberg slopes and plateau, grass species include Monocymbium ceresiiforme, Diheteropogon filifolius, Sporobolus centrifugus, Harpochloa falx, Rendia altera, Cymbopogon dieterlenii, and Eulalia villosa. These most often occur on leached, rocky, shallow soils that are characteristic of moist, cool, and steep mountain slopes. Non-grassy forbs include Helichrysum cerastioides, H. oreophilium, H. spiralepis, Rhus discolor, Selago galpinii, Clutia monticola, and Sebaea dedoides. Among the dominant and diagnostic grass species on the lower slopes of the Drakensberg are Poa annua, Hyparrhenia hirta, Aristida diffusa, and Trachypogon spicatus. The most common secondary grasses in the forest belt on the mountains are Elionurus argenteus, Exotheca abyssinica, Loudetia simplex, Monocymbium ceresiiforme, Themeda triandra, and species of Andropogon, Brachiaria, Digitaria, Hyparrhenia, Pennisetum, and Setaria (Smith and Everson 1985). Non-grassy forbs include Rhus dentata and Leucosidea serice (White 1983; Lubke et al. 1986, Matthews et al. 1993; WWF and IUCN 1994; Burgoyne 1995; Cowling et al. 1997). Some areas have been altered by commercial afforestation, and are used for farming crops such as corn.

Some of Africa’s largest coniferous forests are found here; Podocarpus is the most widespread genus while Widdringtonia is also present (WWF and IUCN 1994). There is evidence from the Vryheid region at Voordrag that Podocarpus forests in the KwaZulu-Natal Midlands were well developed before the Last Glacial Maximum in an area where forests are absent today (Botha et al. 1992). This was not the case for the high Drakensberg as temperatures were probably too low for Podocarpus survival. Dominant canopy species include Maytenus peduncularis, Podocarpus latifolius, Pterocelastrus echinatus, and Scolopia mundii.

Biodiversity FeaturesLesotho and the KwaZulu-Natal Drakensberg form the center of southern Africa’s Afromontane region. Unlike mountains further north where Afromontane communities are found only above 2,000 m, here latitude compensates for altitude, allowing Afromontane communities to occur down to sea level (Dowsett 1986; Cowling et al. 1997).

Hilliard and Burtt (1987) recorded 1,261 species of plants in the southern KwaZulu-Natal Drakensberg alone. An estimated 30 percent of these species are endemic to the Drakensberg Mountain Range (Huntley 1993; Matthews et al. 1993). Grass species and herbs show high diversity, with endemism concentrated in the grasslands of the medium to high altitude slopes (1,500 to 2,500 m). Saniella spp., Rhodohypoxis spp., Gladiolus saundersii, and the orchids Disa fragrans, Disperis wealei, and Brownlea are amongst the Drakensberg endemics (Huntley 1993). Dicotyledons endemic to Lesotho include Glumicalyx lesuticus and Dianthus basuticus var. basuticus, and those endemic to the Drakensberg center are Glumicalyx nutans and Craterocapsa montana (Huntley 1993). In the northwestern parts of the ecoregion, the isolated mountain ranges of the Soutpansberg and Blouberg are particularly important for large numbers of endemic grassland plants. More than 100 endemic grassland species are found on the quartzite and dolomite rocks here (Matthews et al. 1993, Burgoyne 1995; Low and Rebelo 1998).

Animal endemism is not high in most groups, but is pronounced among the reptiles. Twenty- four species occurring within the ecoregion are regarded as strictly endemic, and 38 percent of the reptiles are near-endemic (Branch 1998). Many of the endemic species have been discovered only within the last 10 years. The degree of endemism may be even higher once the ecoregion has been fully explored. For example, recent surveys found an additional six species of dwarf chameleons (Bradypodion sp.) that are still awaiting description (Branch pers comm. 2000). As with the flora, the fauna of the isolated grasslands occurring in the Soutpansberg and Blouberg mountain ranges are also unique and contribute significantly to the high degree of endemism observed. These mountains were once the home of Eastwood’s whip lizard (Tetradactylus eastwoodae), which has not been rediscovered since its description in 1913. Its extinction most likely resulted from the destruction of its original habitat for pine plantations (Branch 1998).

Only one frog is a strict endemic (Breviceps sylvestris), and a further five (Leptopelis xenodactylus, Breviceps maculates, Breviceps verrucosus, Cacosternum poyntoni and Rana dracomontana) are found almost exclusively in this ecoregion (Passmore and Carruthers 1995). Bird species richness is fairly high for the ecoregion. Near-endemics include the bush blackcap (Lioptilus nigricapillus), Drakensberg siskin (Pseudochloroptila symonsi), forest canary (Serinus scotopus), yellow-breasted pipit (Anthus chloris, VU), orange-breasted rockjumper (Chaetops aurantius), buff-streaked chat (Oenanthe bifasciata), and Rudd’s lark (Heteromirafra ruddi, CR) (Harrison et al. 1997; Hilton-Taylor 2000). The ecoregion also contains the last stronghold of the lammergeier (Gypaetus barbatus) in southern Africa.

Some of the largest populations of ungulates in southern Africa are found within the ecoregion, including eland (Taurotragus oryx), reedbuck (Redunca arundinum), mountain reedbuck (Redunca fulvorufula), grey rhebok (Pelea capreolus), black wildebeest (Connochaetes gnou) and a small population of oribi (Ourebia ourebi) (Stuart and Stuart 1995). Two mammals are endemic to the ecoregion, Myosorex tenuis and Ambloysomus gunningi, while Pronolagus crassicudatus is near-endemic. Rowe-Rowe (1982) gives a detailed account of the ecology of the small mammal communities within Giants Park Nature Reserve, one of the ecoregion's largest reserves.

Current StatusThe grassland biome is one of southern Africa’s most endangered habitats (Cowling et al. 1997), primarily as a result of extensive fragmentation due to agriculture. Low and Rebelo (1998) state that 32 to 45 percent of this ecoregion has been converted from natural vegetation to other land cover types. The conservation status is not high, with less than 1 percent of the grasslands officially protected. The mosaic of isolated patches is particularly prone to fire and point exploitation, for example bark-stripping of medicinal trees. Additional threats include: soil erosion, overgrazing, afforestation with exotic trees, firewood collection, and invasion by introduced plants (WWF and IUCN 1994).

The black wildebeest (Connochaetes gnou) is no longer living as a wild animal, and is only found on fenced land. Although populations once dwindled as low as 300 or 600 animals, today around 10,000 animals are found in tightly managed reserves. This ecoregion provides an important location for surviving small herds (Kingdon 1997).

Two of southern Africa’s largest and most well developed reserves occur within this ecoregion. The larger of the two, the Hluhluwe-Umfolozi Park (in KwaZulu-Natal province), has important populations of the elephant, lion, black and white rhino, buffalo, and leopard as well as cheetah (Acinonyx jubatus), wild dogs (Lycaon pictus) and other large mammals. This region also has played a vital role in the restoration of the white rhino (Ceratotherium simum). At the end of the 19th century, this species was near-extinction, and by the 1920’s, Umfolozi Game Reserve harbored all the remaining 50-100 white rhinos in southern Africa. By the early 20th century, Umfolozi and Hluhluwe parks had initiated an endangered breeding center to restore populations of the southern white rhino. Today, virtually every southern white rhino in the world (more than 8,000) are descended from individuals from those reserves (Stoddard2000). Hluhluwe-Umfolozi is now home to approximately 18 percent of Africa's white rhinos and 17 percent of Africa’s black rhinos (Diceros bicornis) (African Wildlife Update 2000).

The second largest reserve is Giant’s Castle Reserve, founded in 1903 to protect the eland, the largest species of antelope. The reserve is also home to Southern Africa’s largest breeding population of bearded vultures (Harrison et al. 1997).

Ostensibly, these reserves fulfill very important conservation functions, yet they protect only a tiny percentage of the habitat, about 1 to 2 percent. The fragmented nature of the landscape makes reserve design particularly problematic. The central portion of these grasslands, moist upland grassland (Low and Rebelo 1998) is poorly conserved, with the major conservation areas being the Coleford and Himeville Reserves in KwaZulu-Natal. In the southeastern portion, there are few conservation areas, although the vegetation is represented in the Mountain Zebra National Park. There are also good areas of this grassland on private estates. The northeastern portion is also poorly protected, but there are areas of the natural vegetation at Blyde River Canyon, Gustaf Klingiel, Mt. Sheba, and Pilgrims Rest Nature Reserves.

Types and Severity of ThreatsIt is believed that the Afromontane forest was previously widespread throughout the ecoregion. Now what remains are only small patches. In areas that have been heavily grazed, the native grassland has been invaded by dense and less palatable grass species, turning the area into what is characterized as "sour veld" (Low and Rebelo 1998). In addition, fires (both wild and controlled burns for tick removal) and grazing by domestic species over many years has heavily altered this ecoregion. These changes pose major threats that have contributed to the loss of most indigenous plant species. Forest margins may be particularly vulnerable to fire because these open scrub formations often have higher available fuel compared to the grassland. Species of Protea are the most characteristic of the secondary montane species that invade after fire, especially at lower elevations.

Justification of Ecoregion DelineationThe linework for this ecoregion was adopted from the ‘Northeastern mountain grassland,’ ‘Southeastern mountain grassland,’ ‘moist upland grassland,’ ‘short mistbelt grassland,’ ‘west cold highveld grassland,’ ‘coast-hinterland bushveld,’ ‘Natal central bushveld,’’subarid thorn bushveld,’ ‘eastern thorn bushveld,’ and ‘Natal lowveld bushveld’ units of Low and Rebelo (1998). This corresponds with White’s (1983) ‘undifferentiated montane vegetation’ unit. The disjunct Soutpansberg montane area, delineated in Low and Rebelo as ‘Soutspansberg arid mountain bushveld,’ was included due to similar biological patterns (e.g. reptiles) to the Drakensberg Montane Grassland. This area encompasses the South African grasslands and inland portion of the South African forests Endemic Bird Areas (Stattersfield et al. 1998), as well as the Afromontane part of Maputaland-Pondoland Center of Plant Diversity (WWF and IUCN 1994).